The core libraries and headers are released under the MIT license. Some modules are under LGPLv2 (see COPYING for details).
Upipe 0.4 (preview release 4) was released on January 30th 2016. You can download the tarball from here (md5 d47786135c50ea3f95d229247ef0dc67).
Development versions can be browsed and retrieved from the development site.